With the epoxy leveling complete on the gantry face, it was time to prepare the Y Axis profile rails and their aluminum bar stock mounts.
When I had mounted the Z Axis rails, I clamped the rails against a straight edge and then used an automatic center punch to mark all the hole positions on the aluminum bar stock. Then I removed the rail and drilled all the holes on the drill press. That turned out to be less than ideal since the center punch was smaller in diameter than the rail mount holes and I wasn’t perfectly centered with each hole. Luckily there was enough play around the M4 screws to correct these minor errors, but I needed a better method for the Y Axis.
Again, I clamped a straight edge against the registration surface on the side of the profile rail, then aligned that with the aluminum bar stock and clamped the bar stock together with the rail. Rather than using the small diameter spring-loaded center punch to mark each hole, I found a drill bit that exactly matched the diameter of the holes in the profile rail. I inserted this bit in each hole and gave it a good tap with a hammer, leaving a mark at the center of each hole. This allowed me to drill all the holes more accurately at the drill press. I still ended up with some slight errors from my less than perfect alignment of the drill bit with the marks on the bar stock. For the second Y axis rail I tried yet another method…third time is a charm!
Leaving the rail/bar assembly clamped together, I brought the whole assembly to the drill press. I aligned the first hole on one end with the drill bit and could easily see when it was centered. I drilled the first hole, then tapped it and put a screw in. Next I drilled and tapped the hole on the opposite end and put a screw in. Followed up with one in the center, gradually removing clamps as I went. Now I could drill all the holes without having to mark anything. This method was much faster and more accurate as well. With the holes drilled and the rail still attached, the rail acted as a guide for the tap to ensure it was vertical. The tapping operation went much faster this way as well.
I didn’t take a lot of pictures of this whole process, but here are a few shots of the work and progress:
Rails laid in place on the gantry for fit check: